Preserve CPS totals in PUF clone collapse

[MaxGhenis]

Summary

• Preserve CPS-measured totals when collapsing PUF support clone tax-detail leaves back to CPS rows.
• Scale taxable/tax-exempt interest, qualified/non-qualified dividends, and taxable/tax-exempt pension components to the CPS-reported total using donor component shares when available and documented fallback shares otherwise.
• Pass through CPS unemployment compensation to taxable unemployment compensation in the collapse path.
• Fix an unrelated calibration_backend="none" summary bug where microcalibrate_constraint_normalization could be referenced before assignment.

Context

Claude iter112/iter115 identified the main remaining replacement blocker: MP should keep CPS-measured income totals on CPS records and impute only missing tax detail / PUF-clone values. The latest 2192907 artifact passed export gates, but its apparent production-eCPS loss win is not promotion-grade because the holdout favors production eCPS and the scorer target DB mis-scores the production baseline. This PR addresses the highest-leverage local passthrough issue before the next rebuild.

Tests

• /Users/maxghenis/.codex-worktrees/microplex-us-rc-main-8fe13c9-20260604/.venv313/bin/python -m pytest tests/pipelines/test_us.py -k "puf_support_clone" -q
• /Users/maxghenis/.codex-worktrees/microplex-us-rc-main-8fe13c9-20260604/.venv313/bin/python -m pytest tests/pipelines/test_us.py::TestUSMicroplexPipeline::test_calibrate_policyengine_tables_none_backend_preserves_original_weights -q
• /Users/maxghenis/.codex-worktrees/microplex-us-rc-main-8fe13c9-20260604/.venv313/bin/python -m pytest tests/pipelines/test_us.py -q
• /Users/maxghenis/.codex-worktrees/microplex-us-rc-main-8fe13c9-20260604/.venv313/bin/python -m ruff check src/microplex_us/pipelines/us.py tests/pipelines/test_us.py